The complete mitochondrial genome of the zebra seabream Diplodus cervinus (Perciformes, Sparidae) from the Mediterranean Sea

Abstract The complete nucleotide sequence of the mitochondrial (mt) genome of the demersal zebra seabream Diplodus cervinus (Lowe, 1838) was determined for the first time. The double stranded circular molecule is 16,559 base pairs (bp) in length and encodes for the typical 37 metazoan mitochondrial genes, and 2 non-coding regions (D-loop and L-origin). The gene arrangement of the D. cervinus mt genome follows the usual one for fishes. The nucleotide sequences of the mt protein coding and ribosomal genes of D. cervinus mt genome were aligned with orthologous sequences from representatives of the Sparidae family and phylogenetic relationships were inferred. Maximum likelihood analyses placed D. cervinus as a sister species of Diplodus sargus (Linnaeus, 1758).

The zebra seabream Diplodus cervinus (Lowe, 1838) is a gregarious demersal marine fish of the family Sparidae Rafinesque, 1818, usually living in groups of 4-5 individuals over rocky bottoms up to 80 m depth, although it can be also found on muddy bottoms up to 300 m (Bauchot and Hureau 1986;Pajuelo, Lorenzo, and Domı nguez-Seoane 2003). This thermophilic species is distributed in the eastern Atlantic Ocean from the Bay of Biscay to Cape Verde Islands, from Angola to South Africa, and around Madeira and Canary Islands, but it also occurs in the Mediterranean Sea, where it is recently widening its distribution (Bauchot and Hureau 1986;Pajuelo, Lorenzo, and Domı nguez-Seoane 2003;Tiralongo et al. 2020). It reaches $55 cm in length and 2.7 kg in weight, and it is a species of interest in small scale fisheries throughout its range of distribution, with scattered attempts to rear it using aquaculture techniques (Bauchot and Hureau 1986;IGFA 2001). This species, together with other ones of the genus Diplodus, represents a candidate with great potential for aquaculture, due to its market price and good adaptability to farming environment (Coutinho et al. 2016). In some coastal areas, like those of Canary Islands, this demersal species covers a relevant ecological role (Pajuelo, Lorenzo, Domı nguez, et al. 2003).
The D. cervinus specimen analyzed in this study was meant for sale as seafood to the consumers. The specimen was caught by local fisherman and it was collected for research as a dead specimen from the fisherman's market (36.7406 N, 15.1193E), where it was supplied directly from local fishermen. Thus, it did not undergo any manipulation or experimentation in the laboratory. Its usage for scientific purposes is not included in the Article 2 of the Italian Legislative The final contig obtained was annotated by the MitoFish server (Iwasaki et al. 2013) and subsequently checked manually.
All protein-coding genes started with the codon ATG except for the subunit 1 of the cytochrome oxidase (cox1) that started with GTG. Some genes had complete stop codons (TAA in nad4L and nad5; TAG in subunit 8 of the ATP synthase (atp8), nad1 and nad6; AGG in cox1), while other genes ended with a single T (cox2, cob, nad3, and nad4) or TA (atp6, cox3, and nad2), which presumably becomes functional by subsequent polyadenylation of the transcribed messenger RNA (Ojala et al. 1981).
A maximum likelihood (ML) analysis was implemented to elucidate the phylogenetic position of D. cervinus. It was performed in RAxML-NG (Kozlov et al. 2019). The resultant phylogeny (Figure 1) placed D. cervinus as sister species of D. sargus (Linnaeus, 1758) with maximum support, and both species as sister group of Diplodus puntazzo (Walbaum, 1792), again with maximum support. So, all three latter species formed a monophyletic group that corresponded to a clade including the species of the genus Diplodus Rafinesque, 1810. This clade was placed in the topology as a sister group of a clade including the species of the genus Acanthopagrus Peters, 1855, with a ML support of 94. This last clade was recovered as sister group of Pagellus acarne (Risso, 1827) and Pagellus bogaraveo (Br€ unnich, 1768), similar to previous studies (Ceruso et al. 2020;Caputi et al. 2021).

Ethical approval
This study has been reviewed by the Ethical Animal Care and Use Committee of the University of Naples Federico II and received institutional approval (Notice No. PG/2022/0093423, July 27 th 2022).

Author contributions
FC, TP and PS conceived and designed the project. VT, RMS, AL, FT, IV and MC performed labwork. DO, LC and FT performed data analyses and interpretation. DO drafted the manuscript. DO, TP, LC, VT, RMS, AL, FT, IV, FB, and PS revised the manuscript for intellectual content and were involved for final approval of the version to be published. All the authors agreed to be accountable for all aspects of the work.

Disclosure statement
No potential conflict of interest was reported by the author(s).

Funding
The author(s) reported there is no funding associated with the work featured in this article.